The present invention relates to a structure for supporting cylinders, which are employed in vehicles such as forkifts and arranged between axles and body frames to restrict the movement of the axles.
Forklifts having rear axles that are supported pivotally with respect to its body frame to permit tilting, or roll, of the forklift are known in the prior art (e.g., Japanese Unexamined Patent Publication No. 58-183307). In such a forklift, a hydralic cylinder is arranged between the body frame and the axle to restrict the pivoting of the axle with respect to the body frame. The hydraulic cylinder locks the axle and restricts tilting of the forklift to maintain stability. For example, the tilting of the forklift is restricted when the forklift carries heavy loads, holds loads at high positions, or turns to change directions at high traveling speeds.
The hydraulic cylinder may be connected to the body frame and to the rear axle. In such case, a bracket having a connecting shaft, which extends in the longitudinal direction of the forklift (the direction of the roll axis), is fixed to the body frame. The hydraulic cylinder has a cylindrical housing. One end of the housing is secured to an anchor. The anchor is pivotally connected to the connecting shaft by means of a bearing such that the hydraulic cylinder is pivotal with respect to the body frame about the connecting shaft. A piston rod extending from the other end of the housing is connected to the rear axle such that the piston rod is pivotal. That is, like the housing of the hydraulic cylinder, the piston is pivotal about an axis that extends in the longitudinal direction of the forklift. Accordingly, the hydraulic cylinder is pivoted relative to the body frame and the rear axle, a pair of axes that extend in the direction of the roll axis.
The rear axle is assembled as a unit, or an assembly, before being connected to the body frame. The dimensional tolerances allowed for the components constituting the rear axle assembly may offset the position of the rear axle relative to the body frame from the ideal location in the longitudinal direction of the forklift. Furthermore, parts connecting the rear axle to the body frame may become loose during use of the forklift. This may also offset the relative position of the rear axle and the body frame. Such conditions would apply excessive force on the connecting shaft, the anchor, the bracket, and other parts of the hydraulic cylinder.
These problems may be solved by a structure such as that shown in FIG. 5. In a similar manner to the structure of the Japanese publication, a bracket 70 fixed to a body frame 75 has two support plates 72 to support a connecting shaft 71. A hydraulic cylinder 77 secured to a rear axle 76 is connected to the connecting shaft 71 with a bearing 74. The structure of FIG. 5 differs from the structure of the Japanese publication in that the distance between the support plates 72 is longer and that the connecting shaft 71 is longer than the diameter of the anchor 73. This permits the anchor 73 to move in the axial direction of the connecting shaft 71, or longitudinal direction of the vehicle. Thus, if the position of the rear axle 71 relative to the body frame 75 is offset longitudinally from the ideal location, the movement of the anchor 73 with respect to the connecting shaft 71 compensates for the offset distance. This prevents excessive force from acting on the bracket 70, the anchor 73, and other parts, while permitting the hydraulic cylinder 77 to pivot about a pair of longitudinally extending axes.
In the structure of FIG. 5, the hydraulic cylinder 77 is moved with its anchor 73 connected to the long connecting shaft 71. Thus, when the rear axle 76 is pivoted with respect to the body frame 75, a bending force is applied to the connecting shaft 71 by the anchor 73. The bending force may deform the connecting shaft 71. Therefore, the dimensions of the connecting shaft 71 and the bracket 70 must be enlarged to withstand the bending force. This increases the space required by the bracket 70.